Pumps for deep-well water lifting Which pump is commonly and successfully used for lifting water from deep wells?

Introduction / Context:
Deep wells pose suction head and priming challenges. Traditional surface-mounted centrifugal pumps cannot lift water much beyond the atmospheric pressure limit. Alternatives place the pumping action down-hole or use methods that avoid long suction lifts. Two proven approaches are air-lift and jet (ejector) systems, each with particular advantages.

Given Data / Assumptions:

• Well depth exceeds practical suction lift of surface centrifugal pumps.
• Desire for simple, robust operation with sandy or gas-laden water possible.

Concept / Approach:
An air lift pump injects compressed air into the riser pipe below the water level, reducing the mixture density and causing the aerated column to rise. There is no moving part down-hole, making it reliable for deep, crooked, or sandy wells. Although efficiency is modest, it is “successfully used” for deep lifts where other pumps face priming or wear issues.

Step-by-Step Solution:
Supply compressed air to an injector at depth.Air-water mixture density decreases in the riser.Buoyancy and pressure differential lift the mixture to the surface.Separate air and water at discharge; recirculate air if desired.

Verification / Alternative check:
Field practice and textbooks list air-lift pumps as suitable for deep wells and abrasive conditions. Jet pumps (ejectors) are also used, but the question emphasizes “successfully used,” a phrasing commonly associated with air lift in exam literature.

Why Other Options Are Wrong:
Surface centrifugal pumps struggle with deep suction. Reciprocating pumps can lift from depth but require long rods/valves and are maintenance-heavy. Jet pumps are viable but often paired with specific sets; many syllabi credit air lift as the standard deep-well answer. Gear pumps are for viscous fluids in process plants.

Common Pitfalls:
Assuming the atmospheric suction limit can be bypassed without special arrangements; ignoring abrasive wear in down-hole mechanical pumps.

Final Answer:
Air lift pump